A bone anchor is provided comprising an anchor member having an open first end, a second end and a tubular section between the first end and the second end, a longitudinal axis extending from the first end to the second end, and a bone engagement structure for engaging the bone in at least a portion of the tubular section, wherein the anchor member is made of a first material. The bone anchor also comprises a core member having a first end and a second end and being insertable into the anchor member and connectable thereto, wherein the core member is made of a second material that is different from the first material.